Our long term objective is to understand the mechanism of tissue specific gene regulations. The aim of the research described here is to locate and characterize the proximal cis-acting control elements that regulate tissue-specific gene expression of the alcohol dehydrogenase (ADH) gene in Drosophila melanogaster. The strategy that we have been (and will be) using to help achieve the stated aim consists of three steps: First, we will generate a great number and variety of aberrations (deletions, duplications, inversions, transpositions, substitutions and insertions) in the non-protein coding regions of a series of ADH genes; Second, we will introduce these modified genes into ADH- negative embryos of Drosophila melanogaster; and Third, we will correlate any departures from normal gene activity with the modifications that we had introduced. In this way, we hope to deduce which sequences are active in controlling tissue- specific gene expression and identify the mechanism by which they act. In order to work best, the strategy depends on using a rapid and quantitative method for evaluating tissue-specific gene activity in transformed animals, free as much as possible from fluctuations of activity due to the random positioning of introduced genes within the genome. We have recently developed such a method. We call it "somatic transformation." Animals will be injected with the modified genes as embryos and ADH activity and RNA will be measured in the larvae and adults that develop from the injected embryos. Both quantitative and qualitative experiments will be carried out. Gene activity will be qualitatively measured by in situ histochemical staining for ADH activity. Quantitative assays will measure ADH activity and ADH-specific RNA relative to that of a control gene located on the same (or on a simultaneously injected) plasmid. This work will lead to an increased understanding of the mechanism of gene control in higher organisms, and as such, should prove valuable in elucidating how things go wrong in the disease state. Thus what we learn here will have relevance in the understanding and eventual treatment of hereditary defects and cancer.